Cooling Pack With Low Internal Air Volume

ABSTRACT

An embodiment of is cooling pack  110  having at least two components that cause an endothermic reaction when mixed together. At least one of the at least two components being in liquid form  410  and contained in, or separated from, the other at least one component  430  by a frangible membrane  150.  The at least two components ( 410, 430 ) contained within a vacuum sealed common envelope  120.  Other embodiments are described and shown.

BACKGROUND U.S. Patents

Patent Number Kind Code Issue Date Patentee 6,099,555 Aug. 8, 2000 Sabin 6,513,516 B2 Feb. 4, 2003 Sabin 7,744,940 B2 Jun. 29, 2010 Hickey

Application Number Kind Code Publication Date Applicant US2011/0022137 A1 Jan. 27, 2011 Ennis-Thomas

BACKGROUND OF THE INVENTION

Cold packs, also known as cooling packs, operating used on endothermic chemical reactions, have been in widespread commercial use fur decades. Early patent literature on these devices dates back at least as far as 1933 when Levenson et al (U.S. Pat. No. 1,894,775) revealed that various salts combined with certain liquid solvents, including potentially water, caused an endothermic reaction, absorbing beat from the environment. Levinson et al farther revealed that placing these chemicals in a “suitable container” created a cold pack.

The commonly found bag-inside-a-bag arrangement of chemical cooling pack design was patented by Robbins in 1959 (U.S. Pat. No, 2,907,173). In this design, still in widespread use today, the inner bag is particularly frangible, or easily broken or ruptured under pressure, while the outer bag is designed to be particularly durable, resisting tearing or leakage even while the inner bag is being burst by squeezing it through the outer bag.

In storage, the liquid components of a chemical cooling pack are usually contained in an inner bag that serves to isolate the liquid contents from the remaining contents of the outer bag, thus preventing the start of the chemical reaction that will cause the cooling reaction. The outer bag provides a common envelope containing both the inner bag and a second chemical component, or set of chemical components, that are typically solids, usually in the form of pellets or powder. When the inner bag is burst, the contents of the two compartments within the common envelope intermix initiating, or activating, an endothermic reaction providing cooling for the desired usage.

There are a number of problems with the current design of cold packs. One problem is that the packs contain a great deal of free air space within the common envelope. This air space makes it difficult to feel the internal bag through the common envelope, this making it difficult to find, squeeze, and burst the internal bag to activate the cooling pack.

The typical cold pack also has the internal bag floating free and mixed in with the solid particulate within the common enclosure making it even more difficult to find the internal bag as it could be anywhere within the internal space of the common envelope.

Another problem caused by the free air within the common envelope, in combination with any free air contained within the internal bag, is that it creates an air gap at the top of the bag as the chemical mixture, once activated, falls to the bottom of the common envelope. This is a particular problem when the cooling pack is used for therapeutic purposes. If the pack is wrapped around a body part for the purpose of cooling the area in contact with the cooling pack, there will be a gap in cooling where the air inside the pack is voiding the cold chemical content.

Additionally, the free air within the common envelope creates the potential for accidentally bursting the common envelope when attempting to burst the internal frangible bag, which could possibly harm the user by bringing their skin in contact with the internal chemicals. The extra air within the common envelope can make it difficult to burst the internal pack without also pressurizing the common envelope. This problem is exacerbated when the cooling pack is used at altitude. For example, at as ski area base altitude of 9600 feet the volume of air inside the pack will expand by approximately 40%.

The current design of cold packs can also have the problem that they can require a fair amount of hand strength to burst the internal bag and activate the cold pack. This can be a problem for the elderly or for a patient that is somewhat incapacitated by injury.

It is this combination of deficiencies and problems that the invention described herein is designed to resolve.

Sabin (U.S. Pat. No. 6,099,555) describes a gelling cold pack technology wherein “one type of zone might be vacuum sealed before the loading of the other type of zone” and that the zones are arranged within the “container”, or what this application refers to as a “common envelope.” In the Sabin patent, the zones contain the various individual components necessary to create an endothermic reaction. Placing a “zone” that has been vacuum sealed, along with one or more additional zones, into the common envelope and leaving free air within this common envelope container, results in all of the problems previously described, because: i) the zones can be located anywhere within the common envelope and ii) the common envelope can contain a large quantity of free air, thus making it difficult to find, squeeze, and burst the liquid pack within this container. Additionally, the free air inside the common envelope may make the common container susceptible to bursting when the end user is attempting to activate the cold pack by bursting the internal liquid container.

In Sabin et al (U.S. Pat. No. 6,513,516) vacuum packing is again described but it is only with reference to a single zone and in specific only to the “heat generating elements.” In this case, the purpose of the vacuum packing appears to be to prevent early initiation of a reaction. Once again, the vacuum sealing is done only to a single zone and prior to packaging all the components within the common container and therefore not resolving the design deficiencies previously described.

Hickey (U.S. Pat. No. 7,744,940) describes a Food Product Warming or Cooling Package. Hickey describes the “package of claim 1 wherein at least one of the pair of compartments in the temperature-changing element is vacuum-sealed” but Hickey does not address the free air within the “enclosure.” This is, once again, because the purpose of vacuum sealing in Hickey is to “prevent any premature reacting of the reagent 66 sic 68 with any carbon dioxide or moisture contained within the ambient air present within the compartment 66.” Therefore, the design of Hickey has the same deficiencies described above in terms of having to blindly locate the specific compartment to be burst within the common enclosure and then having to safely burst it open without potentially bursting the common enclosure open as well.

Ennis-Thomas et al. (Pub. No.: US 2011/0022137) describes a cooling garment with satchels of solid reactant that are vacuum sealed within “frangible satchels.” This creates a number of problems compared to sealing the liquid component within the frangible container. First, it is considerably more difficult to ensure that the solid material is fully dispersed from the frangible satchel after bursting because solids do not flow naturally the way liquids do. Next, it is possible that the process of vacuum sealing solid material inside a frangible membrane will burst the frangible container because the internal solid materials will not necessarily conform to the membrane in the manner that a liquid would. Additionally, when squeezed by the end user, the vacuum-sealed solids will not push out and easily rupture the frangible membrane, because vacuum-sealed solids tend to form into a semi-solid mass that does not move or slide against itself when squeezed.

BRIEF SUMMARY OF THE INVENTION

In accordance with one embodiment, a chemical cooling pack comprises at least two components that when mixed together cause an endothermic reaction. At least one of the two components is in liquid form and is separated from the remaining components by a frangible membrane. The components are vacuum sealed within a common envelope.

DRAWINGS

FIG. 1. Cooling pack partially assembled showing fixedly-positioned liquid component

FIG. 2. Cooling pack common envelope with external markings

FIG. 3. Cooling pack fully assembled and vacuum sealed—Front View

FIG. 4. Cooling pack fully assembled and vacuum sealed—Bottom View in Cross Section

DETAILED DESCRIPTION OF THE INVENTION

The cooling pack of this invention is a chemical cooling pack. It operates based on an endothermic reaction. These common devices function by combining two or more chemicals, or combinations of chemicals, that, upon reaction, absorb heat from the environment. The typical cooling pack contains a solid form component and a solvent. Some of the more common solid form components used in cooling packs include the chemicals ammonium nitrate and urea, but these are only two of many possible solids, The solvent used is typically in liquid form and is usually water; although, again, many different liquid form components are possible. Typically the solid chemicals are included in the cooling pack in either powder form or as small pellets or crystals. When these solids are mixed together with the solvent, typically inside a sealed container, the solids rapidly dissolve and absorb heat, thus creating a useful device for cold therapy or for other industrial or home uses such as food cooling.

In a conventional commercial cooling pack there are two separate locations that contain free air. Free it is air that can be readily removed from the system. The first location is in the packet, container, or compartment that contains the solvent, also referred to as the liquid packet. This is usually a heat sealed plastic (polymer, or other plastic-like material) packet that contains water and a significant amount of air. Air is probably left inside the liquid packet to make the heat sealing process easier. Heat sealing a liquid packet with an air pocket above it is considerably easier than heat sealing a packet while voiding all possible free air because water can encroach on the seal creating gaps in the seal. Note that by voiding the free air this does not include, for example, voiding the air that might be dissolved in the solvent. Instead what is voided is the easily-accessible air that, for example, rests above the liquid.

An important design aspect associated with packaging, or enclosing, the liquid form component without free air in the liquid packet is that the liquid packet should be able to withstand approximately 10% volume expansion. This would allow a cooling pack, which is using water as the solvent, to be stored at temperatures below freezing without rupturing. This is needed because water expands slightly less than 10% when it turns to ice. Such a design can be accomplished in a number of different ways including, using a material for the frangible membrane that will allow at least 10% expansion before it ruptures, or by filling the liquid packet to only 90% of its total capacity.

In this invention it is advantageous, but not required, to void as much of the free air in the liquid packet as possible, for reasons that are explained later in this specification.

The second location that typically contains a great deal of free air is the compartment that holds the solid chemical, along with the liquid packet. Once the two compartments are combined, usually by the end user squeezing and bursting the liquid packet located within the common envelope, or container, that holds both chemicals, the free air in both compartments is combined in the common envelope creating the problems previously discussed in the Background of the Invention section. In many commercial cooling packs the air space in the common envelope can be one quarter to one half of the total internal volume, particularly when the pack is used at altitude.

The current embodiment eliminates this free air space, particularly from the solid compartment of the cooling pack. In the current embodiment of this device, shown under construction in FIG. 1, the cooling pack 110 is made up of a common envelope 120 that, when construction of the cooling pack is complete, forms a pouch or container that houses the liquid packet 140 (drawn in dotted lines to indicate its position on the inside of common envelope 120), with a frangible membrane 150 separating the liquid chemical, or liquid form component, from the solid chemical or solid form component, prior to activation.

In the embodiment shown in FIG. 1, the liquid form component is sealed inside membrane 150 to retain its liquid contents in the same manner that the common envelope is to be sealed. The common envelope is a folded sheet of plastic, sealed on the remaining unfolded three sides 130, 160 and 170 to form a sealed rectangular container. Thus, the two components, the liquid form component and the solid form component, are contained within the common envelope 120. The sealing is typically performed by heat sealing, which is a very simple, well known, inexpensive, and effective process providing a complete seal to isolate the contents from other components. For purposes of the current invention, other similar sealing techniques including but not limited to adhesive layers, radio-frequency (RF) welding, or ultrasonic welding would provide the same construction result as heat sealing.

In the preferred embodiment, once the liquid component is sealed inside its own individual packet, it is then heat sealed to a specific location on the inside wall of the common envelope 120. This might be done, for example, with a single heat seal along one or two of the previously made seals 130 and 170. Alternatively, it might simply be attached with a single drop of adhesive, or with a piece of tape or other attachment feature, to the same predetermined location.

This internal fixation of the liquid component to a specific location within the common envelope is a considerable improvement over the current assembly technique that typically leaves the liquid packet floating freely around the inside of the cold packet amidst the solid form component. Fixing the location of the liquid form component on the inside of the common envelope 120 also allows that location of the liquid packet to be labeled on the outside of the common envelope 120. An example of this labeling 250 is shown in FIG. 2. This eliminates the difficulty of trying to feel through the outside of the cooling pack for the location of the liquid packet and then trying to separate it from the solid form component and manipulate it into a position where it can be grasped and squeezed to cause it to burst.

FIG. 2 shows the outside of the common envelope 120 of cold pack 110 with marking 250 clearly indicating the location where the liquid form component is attached, or in some other manner fixedly positioned, inside the cooling pack 110. FIG. 2 also shows the locations of the three heat seals 220, 230, and 240, which will be created to seal the liquid form component and the solid form component inside common envelope 120. Typically in constructing cooling pack 110 with a linear heat sealer, two of the three heat seals, for example 240 and 230, would be performed first to create an open pouch into which the solid form component could be added. Once the appropriate amount of solid is added a final heat seal 220 would be made to fully seal the cooling pack 110.

In the preferred embodiment the final heat seal would be performed in a vacuum sealing operation to remove the free air from the inside of common envelope 120. FIG. 3 shows the fully sealed cooling pack 110 with a heat seal 310 running on the three sides of the common envelope 120 that are not already sealed by simply folding the plastic of the common envelope 120. Clearly one could also create a very similar package by cutting two equal size pieces of plastic and heat sealing all four edges of the common envelope 110.

There are many potential techniques for vacuum sealing. In general it involves applying a vacuum to as closed space and then sealing the space shut with the vacuum still in place. One straightforward method for sealing the cooling packs of this invention would be to seal all four edges (or three if one side of the envelope has been folded over) leaving a very small segment of the final seal incomplete. For example, the leftmost edge of the top of heat seal 310 could be left incomplete. A tube could then be inserted a short distance into this small opening in the seal. If the seal between the tube and the common envelope is sufficiently tight, a vacuum pump applied to the outside end of the tube would draw out virtually all of the free air within the common envelope 110. After the free air was withdrawn by the vacuum pump, the heat seal could be completed by sealing just inside of the where the tube entered the common envelope while maintaining the vacuum. An example of the location of such a seal is indicated in FIG. 3 by the space outlined by dashed lines 320.

FIG. 4 shows a cross sectional view of cooling pack 110, after vacuum sealing, as viewed from the bottom edge of the cooling pack in FIG. 3. The liquid form component 410, in the embodiment shown in FIG. 4, is confined between membrane 150 and common envelope 120. In this case membrane 150 is heat sealed (or affixed in some other manner) directly to the inside of the common envelope, thus forming a pocket between the common envelope and the rest of the internal contents of the common envelope. The solid form component 430 is packed tightly together by the vacuum sealing operation, thus leaving substantially no free air within common envelope 120.

Obviously the solid form component, whether in powder form or pellet form, does not pack perfectly within the common envelope 120 regardless of the extent of the vacuum drawn by the vacuum sealing process. There will be air trapped in and among the particles of the solid term component. This trapped air is not considered to be free air for the purpose of this disclosure.

Noting how the vacuum sealing process tightly packs the internal contents of the cooling pack, it is also possible to create a cooling pack where the location of the liquid packet, with its internal liquid form component, is confined to a fixed, predetermined internal location simply by positioning the liquid packet 140 in the desired location prior to vacuum sealing the outside envelope of the cooling pack. If there is a sufficient vacuum inside common envelope 120 after sealing, the friction between the solid form component 430, the liquid packet (410 surrounded by membrane 150), and the inside of common envelope 120 will hold the liquid packet in place, not allowing it to move until it is ruptured to initiate the endothermic reaction of the cooling pack.

Membrane 150 is a frangible membrane, in that it is, by design, weaker than the plastic used in the common envelope 120. It is designed to rupture or burst when the pressure of the liquid form component 410 is increased by squeezing or striking the liquid packet 140 through the common envelope 120. Upon rupturing the frangible membrane the liquid form component 410 spills out into the common envelope 120 mixing with the solid form component thus initiating, or activating, the endothermic reaction of the cooling pack 110.

Conversely, common envelope 120 is designed to withstand the pressure required to burst the internal frangible membrane 150, surrounding the liquid form component 410, without itself bursting. The possibility of bursting the common envelope while attempting to activate a cooling pack however remains a risk and safety concern for most commercial cooling pack designs. In contrast, in the current invention vacuum sealing serves to substantially eliminate the possibility of creating sufficient internal burst pressure on the common envelope 120, while attempting to burst the liquid packet 140, to also rupture the common envelope 120. This is an added margin of safety provided by the current design.

An additional advantage provided by the current design is the ability to burst the liquid packet 140 by striking the cooling pack 110 at a clearly-marked location rather than having to try to squeeze the liquid packet as is currently required by the design of typical commercial cooling packs. By vacuum sealing the common envelope 120 with the liquid packet 140 in a known marked location the cooling pack can be activated by a simple strike, for example with the side of the list or even with the fiat of a book, which will easily burst the liquid packet 140 without generating undo pressure on the common envelope 120. This eliminates the requirement for having a great deal of hand strength to activate the cooling pack.

The previous discussion of the embodiments has been presented for the purposes of illustration and description. The description is not intended to limit the invention to the form disclosed herein. Variations and modifications commensurate with the above are considered to be within the scope of the present invention. The embodiments described herein are further intended to explain the best modes presently known of practicing the invention and to enable others skilled in the art to utilize the invention as such, or in other embodiments, and with the particular modifications required by their particular application or uses of the invention. It is intended that the appended claims be construed to include alternative embodiments to the extent permitted by the prior art. 

1. A cooling pack comprising: a. at least two components that cause an endothermic reaction when mixed together; b. at least one of the at least two components being in liquid than and separated from the other at least one component by a frangible membrane; c. the at least two components contained within is common envelope; d. the common envelope being vacuum sealed.
 2. The cooling pack of claim 1 wherein the common envelope substantially contains no free air.
 3. The cooling pack of claim 2 wherein the liquid form component contained in, or separated from, the other at least one component by a frangible membrane forms a liquid packet and the liquid packet substantially contains no free air.
 4. The cooling pack of claim 1 wherein the at least one component in liquid form and contained in, or separated from, the other at least one component by the frangible membrane is fixedly positioned within the common envelope.
 5. The cooling pack of claim 4 wherein the external surface of the cooling pack includes labeling to indicate the internal position of the at least one component in liquid form.
 6. The cooling pack of claim 4 wherein the fixed position of the at least one component in liquid form is provided by internal fixation to the common envelope
 7. The cooling pack of claim 4 wherein the at least one component in liquid form is fixedly positioned within the common envelope by the vacuum sealing of the common envelope.
 8. A method for manufacturing a cooling pack comprising the steps of: a. providing a plurality of components that cause an endothermic reaction when mixed together; b. providing at least one of the plurality of components in liquid form; c. separating the at least one liquid form component from the remaining plurality of components by a frangible membrane; d. packaging the plurality of components within a common envelope; e. vacuum sealing the common envelope.
 9. The method of claim 8 wherein the step of vacuum sealing substantially removes free air from the common envelope.
 10. The method of claim 8 wherein the step of separating the at least one liquid form component from the remaining plurality of components by a frangible membrane includes enclosing the liquid form component with a minimum of free air.
 11. The method of claim 8 wherein the step of separating the at least one liquid form component from the remaining plurality of components by a frangible membrane includes positioning the at least one liquid form component in a predetermined location within the common envelope prior to sealing the common envelope.
 12. The method of claim 11 including the step of marking the external surface of the common envelope to indicate the internal position of the at least one liquid form component.
 13. The method of claim 11 wherein the step of positioning the at least one liquid form component in a predetermined location is accomplished by internally affixing the frangible membrane to the common envelope.
 14. The method of claim 11 wherein the step of positioning the at least one liquid form component in a predetermined location is accomplished by vacuum sealing the at least one liquid form component, separated by the frangible membrane from the remaining plurality of components, in a predetermined position within the common envelope.
 15. A cooling pack comprising: a. at least two components that cause an endothermic reaction when mixed together; b. at least one of the two components being in solid form; c. at least one of the two components being in liquid form; d. the liquid form component separated from the other components by a frangible membrane; e. the frangible membrane with the liquid component fixedly positioned within a common envelope; f. the external surface of the common envelope marked to identify the position of the liquid form component; g. the common envelope vacuum sealed to eliminate the free air. 